Mattel created catalogs for toy store owners to use as a reference as they ordered, or re-ordered, merchandise. M.U.S.C.L.E. first appeared in Mattel’s 1986 catalog. The next year was the final one for M.U.S.C.L.E in the Mattel catalog. The 1987 catalog makes it clear that M.U.S.C.L.E. was not a top priority.